A National University of Taiwan buoy recorded a pressure low of 897 millibars in the eye of Nepartak late on Thursday night, local time. Pressure lower than 900 millibars is rare, says tropical meteorologist at the University of Melbourne, Kevin Walsh.

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“If the central pressure of the typhoon is a lot lower than the pressure of the surrounding atmosphere, all the air rushes towards the centre and the rotational movement of the earth spins it in a vortex,” he says. The lower the pressure of the eye of the typhoon, the more intense it is.

More than 15,000 people have been evacuated from their homes, with many flights cancelled and schools and offices shut. Soldiers have been deployed across the island to help with the disaster relief.

The storm is expected to linger over Taiwan for up to eight hours, before making landfall in China’s Fujian province on Saturday morning.

Although wind speeds are expected to fall to around 17 kilometres per hour by the time the typhoon reaches mainland China, torrential rain is set to exacerbate local flooding that has left 140 people dead or missing. It is being described as the worst flooding since 1998.

As Taiwan recovers from its first major tropical storm of the season, and China prepares for a further deluge, scientists warn that climate change could increase the intensity of typhoons in the years to come.

“A cyclone is a bit like a steam engine,” says Walsh. “Steam engines have a heat source and a cold surrounding bit. The heat source for cyclones is the ocean, and the cold part is the top of the storm. Climate change projections show that the difference in temperature between these two things is likely to increase, making the steam engine more efficient.”